Perhaps you should try some spelling variations:
"modified coverage approximation algorithms" » "modified average approximation algorithms"
"modified using classification algorithm" » "modified blind classification algorithm", "modified binary classification algorithm", "modified _ classification algorithm", "modified caging classification algorithm"

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (("modified coverage approximation algorithms") OR ("modified using classification algorithm"))~.
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